Thermal conductivity of rock-forming minerals

A new method has been developed to measure thermal conductivity of monomineralic aggregate at ordinary temperature and pressure, in which the needle-probe technique is applied to a mixture of powdered specimen and distilled water. By use of this method, thermal conductivity of 166 rock-forming minerals has been determined. The results are discussed in relation to the density, crystal structure, and chemical composition of the minerals. The major conclusions are: (1) for most of the minerals, thermal conductivity is a linear function of density for constant mean atomic weight; (2) the conductivity of silicates is controlled by the structure of the silicon-oxygen network and is lower for the more complicated networks; (3) in an isomorphous series (garnets, pyroxenes, amphiboles, and carbonates), the thermal conductivity decreases as the mean atomic weight, or the mass of metallic ions, increases; (4) in a series that forms a binary solid solution (olivine, pyroxene, and plagioclase), the conductivity has a minimum at an intermediate composition; (5) the thermal conductivity of silicates is related linearly to elastic-wave velocities.